With the wide application of the liquid crystal display device, users raise higher and higher requirements for the liquid crystal display device, especially in terms of increasing the aperture ratio. The “aperture ratio” refers to the ratio of an area of a portion of a pixel where light is transmitted to the entire area of the pixel without considering the wiring portion and the transistor portion (which are generally blocked by a black matrix) of the pixel. The higher the aperture ratio is, the more the light is transmitted.
At present, a pixel electrode layer in the liquid crystal display device is formed by a sputtering process after forming a passivation layer. The whole pixel electrode layer is provided in a same plane, i.e. it belongs to a same layer. FIG. 1 is a schematic view illustrating a pixel structure of a conventional array substrate. In FIG. 1, the reference number 101 denotes a gate line layer, the reference number 102 denotes a data line layer, and the reference number 103 denotes a pixel electrode layer. As shown in FIG. 1, the pixel electrode layer 103 is provided in a same plane, i.e. it belongs to a same layer.
FIG. 2 is a cross-sectional schematic view illustrating a region a in FIG. 1. As shown in FIG. 2, a gate line layer 101, a gate insulation layer 104, an active layer 105, a data line layer 102 (comprising a source electrode 1021 and a drain electrode 1022), a passivation layer 106 and a pixel electrode layer 103 are sequentially formed from bottom to top, and the pixel electrode layer 103 is connected to the data line layer 102 through a via hole in the passivation layer 106. FIG. 3 is a cross-sectional schematic view illustrating a region b in FIG. 1. As shown in FIG. 3, this region b comprises the gate insulation layer 104, the data line layer 102, the passivation layer 106 and the pixel electrode layer 103 that are sequentially formed from bottom to top.
In the conventional array substrate as described above, since the pixel electrode layer is provided in the same plane (i.e. merely one pixel electrode layer is provided), pixel electrodes of adjacent pixels cannot be too close to each other. If the pixel electrodes of adjacent pixels are too close to each other, the pixel electrodes of adjacent pixels may be not completely separated from each other due to the limitation of the precision of the etching process, and thereby connections between pixel electrodes of adjacent pixels are caused. If the connections between the pixel electrodes of adjacent pixels occur for the pixel electrodes of adjacent pixels are not completely separated from each other by the etching process, the pixel electrode material remained between the pixel electrodes of adjacent pixels participates in the image display and an undesired bright spot is resulted. At present, a relatively large gap (which is determined according to the precision of the etching process) is provided between the pixel electrodes of adjacent pixels in order to solve the above-described problem. However, in the case that the relatively large gap is provided between the pixel electrodes of adjacent pixels, the area of the pixel electrode is reduced, and thereby the display region is reduced and the aperture ratio is reduced as well.